The mechanisms used in making furniture that is intended to be converted between a sitting unit, e.g., a chair or sofa, in the closed position and a bed in the open position are usually very complicated. These mechanisms include springs, bars, and hinges which may damage sheeting or upholstery. The user may also catch his or her fingers in these mechanisms and receive physical injuries. Such conventional conversion mechanisms have been relatively difficult and complicated to use, especially for the elderly, children and the handicapped.
Furthermore, these mechanisms increase the weight of the furniture, making it more difficult both to move the furniture and to convert it. In addition, these mechanisms often require substantial volume, adding to the volume occupied by the furniture. This is usually apparent in an increase in the depth of the furniture, which is undesirable since space is often at a premium.
Prior attempts to overcome these problems are addressed in U.S. Pat. Nos. 4,953,242 and 5,038,421 of the present inventor. In these patents a sofabed is described in which a sliding support mechanism can be drawn out from the base of the sofa in order to create a bed. The mechanism in U.S. Pat. No. 4,953,242 has a single sliding support that essentially doubles the size of the seating area to form a bed. While this mechanism does reduce the difficulty in changing from a sofa to a bed and does reduce the weight, the bed area is not very large. Also, because of a storage area, when the mechanism is closed to form a sofa, there is a reduced seating area and this area needs to be moved when it is converted into a bed, thus complicating the mechanism. The arrangement in U.S. Pat. No. 5,038,421 uses a double sliding support and an unfolding triple mattress that forms the back of the sofa with one fold and doubles to form two folds that comprise the seat of the sofa. A pillow is folded to provide support at the intersection of the top section and the other two sections of the mattress in the closed or sitting configuration. When the sofabed is opened, the pillow is unfolded to function as a pillow for the bed and the double part of the mattress unfolds to provide a portion of the bed. With this arrangement the sofa has an uncomfortable straight vertical back.
It would be an improvement in these prior designs if the storage area were modified or removed to simply conversion. Also, it would be beneficial if some means were provided to allow the legs of the sliding support to travel over a wood floor or carpet without damaging the floor or becoming snagged on the carpet. Further, it would be beneficial if the backrest of the sofa could be at a more comfortable incline.